Lecture 2 (Intro to MedChem)
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
卡片预览 (24 张)
Free bases or acids are often ____
liquid (oils)
Are they better or worse than a salt?
WORSE • less water soluble than ionized form • difficult to measure (because they are hygroscopic) • difficult to make into a dosage form • less stable
Why do we want to make a salt out of the free acids/bases?
because they are easier/better to work with (see previous card) and are more stable
Drug absorption across biological membranes is better in the ______ state
unionized
T or F: good drugs have only either lipid or water solubility
FALSE -most efficient drugs have some degree of water and lipid solubility
explain solubility
for a chemical to dissolve in a particular solvent the compound must be able to form attractive forces with the molecules of the solvent
it is possible to estimate the solubility properties of drug by examining its _____
structure
Can we alter the solubility of a drug? explain the 3 ways
YES -use acid or base to make the drug into a salt OR -add substituents that are very water soluble: -adding groups that are H bond donors and acceptors -adding groups that can ionize OR -changing dose form
Are dispersion forces strong or weak?
weak
Dispersion forces are called ??
london forces (wrongly called van der waals attraction)
Where do dispersion forces occur?
between induced and instantaneous formed dipoles
As molecule gets larger, dispersion forces get _____
larger disperson forces increase as the total area for interaction between molecules increases
Why do larger molecules become liquids? (ex. butane, hexanes, and octane are liquids but methane, ethane, and propane are gases)
increasing size = increasing dispersion forces also increasing weight is a factor
What is stronger: dispersion forces or dipole-dipole bonds?
dipole-dipole bonding
Where does a dipole-dipole bond occur?
happens between permanent dipoles note** these are not formal charges (that would be an ionic rxn)
H-bonding is a special kind of ??
dipole-dipole bonding
H-bonding is _____ than ordinary dipole-dipole bonding
stronger
When does H-bonding happen?
-happens between atoms with highly electronegative atoms attached to H
H-bonding plays a big role in making things more ??
hydrophilic (water soluble)
Molecules with many H-bond donors and acceptors are more ____ soluble
water
What is the H-bond donor?
electronegative atom with an attached hydrogen
What is the H-bond acceptor?
electronegative atom with a FREE (not tied up in resonance) lone pair of electrons
Are S, Cl, and F, weak or strong H-bond acceptors?
weak
SH is NOT an H-bond ____
donator